Compression therapy

November 20, 2013

DR KENNETH WONG looks at the causes and treatment of chronic venous disease and discusses the benefits and risks.

A common diagnosis that I often encounter in older patients is that of “chronic bilateral leg cellulitis”. So frequent is this condition that a recent literature search on PubMed revealed not a single case report, not a pandemic, but a multitude of related articles linked with that disturbing word “misdiagnosis”. Small wonder. These patients are often subjected to multiple courses of antibiotics without any apparent response, much to the frustration of their clinicians. Surely, pun unintended, something else is afoot?

Chronic (“longstanding”) bilateral (“both left and right”) leg cellulitis is rare. True cellulitis, which refers to infection of the deeper layers of the skin, seldom occurs on both legs simultaneously. More often than not these patients are suffering from another condition called chronic venous disease.

Chronic venous disease

Chronic venous disease is a spectrum of conditions affecting the legs, ranging from red swollen legs (“cellulitis” to the uninitiated) to overt venous ulcers. They stem from leg vein failure, which is referred to by the term “venous incompetence”. Just like doctors, a wayward human organ can have undesirable consequences if left unchecked!

To understand chronic venous disease, one has to challenge basic Newtonian physics and agree that what goes down must also come back up – or face the wrath of disease. Let me explain. The heart pumps blood down to the feet. Blood from the feet must now make its long journey, against gravity, back to the heart. How it accomplishes this is by an ingenious combination of the calf muscle pump and one-way valves in the veins. Blood from the skin collects in the superficial veins. The blood is then channelled to the deep veins (as opposed to superficial) that are enclosed deep within the calf muscles. The channel between the superficial and deep veins is made up of “perforating” or “communicating” veins. During exercise, the calf muscles contract and the deep veins are compressed. The resulting high pressure forces blood in the deep veins to move upwards against gravity towards the heart. One-way valves in the perforating veins prevent back-flow of blood back to the superficial veins.

Trouble begins when the one-way valves fail. Instead of travelling north, high-pressure blood channelled backwards via the perforating veins into the low-pressure superficial veins. The superficial veins, now engorged with blood, become grossly distended, leading to the formation of unsightly “varicose veins”. Blood pools in the lower legs, giving the appearance of swelling, and skin injury ensues over time. The lower legs become red, scaly, painful and itchy: the hallmarks of stasis (“standing still”) eczema. Eventually the skin may die, leaving behind venous ulcers, the final stage of chronic venous disease.

Treatment options

How do we treat chronic venous disease? Elevating the legs is an obvious solution, and indeed, I recommend my patients to do this at every opportunity. However, for this to be effective, the ankles must be raised above hip level – not always an easy manoeuvre for older patients!

A more practical treatment involves compression therapy. Since the nineteenth century, it has been recognised that a compression bandage applied to the lower legs could heal venous ulcers. External pressure provided by the bandage forces the blood from the superficial veins back to the deep veins, thus reversing the effects of venous incompetence.

The degree of compression should be greatest at the ankle and reduce progressively towards the knee to replicate the incremental pressure provided by calf muscles.

This provides the basis of the term “graduated compression bandaging”. A major advantage of this treatment is the preservation of patients’ mobility – as opposed to prolonged bed rest for leg elevation to be effective.

The bandages are available in different levels of compression: light, medium, and high. Selection of appropriate bandages is dependent on the degree of leg swelling and the presence of ulcers. It follows that grossly swollen legs will benefit from high-pressure bandages, whilst early varicose veins can be managed with light compression. Light compression in early venous disease and will halt the progression to venous ulceration.

High-compression therapy is provided by four-layer bandaging, so-called because four layers of bandages are used. Pressures of up to 35-40 mmHg at the ankle are achieved. Different versions of four-layer compression have been described; the original Charing Cross four-layer bandage system utilises, in order of application, orthopaedic wool, cotton crepe, elastic bandage, and cohesive bandage. It is crucial to apply padding over bony prominences that may otherwise be injured from the excess pressure applied. The bandages should be changed every 1-2 weeks, or more often for wounds with heavy exudate.

Compression bandages can be a labour-intensive undertaking; another alternative is to utilise compression stockings. These are graded based on the pressure applied at the level of the ankle. “Class I” stockings provide the least pressure and are suitable for mild swelling, while “Class II” and above are better suited for more severe varicose veins and to treat venous ulcers. The stockings come in different lengths and materials. They are frequently worn just below the knee. In some cases, thigh length stockings are necessary for more extensive swelling. Unlike bandages, compression stockings are easily worn and removed; nursing assistance is seldom necessary and patients generally find them more acceptable. All these factors will undoubtedly improve patient compliance.

Compression therapy caution

Compression therapy comes with a caveat: it is paramount to exclude arterial vascular disease prior to initiation of treatment. Remember that the leg receives oxygen from blood supplied by arteries emanating from the heart. In arterial vascular disease, the vessel walls become narrowed from the accumulation of cholesterol. Blood flow diminishes with time. It doesn’t take much external pressure from bandages to block these vessels completely, with catastrophic results! I routinely order a simple investigation, known as the Ankle Brachial Pressure Index (ABPI) measurement, to determine lower leg arterial pressure prior to compression therapy. This is easily performed with a hand-held Doppler machine at the bedside. A low ABPI is indicative of arterial vascular disease. Compression therapy must be avoided in this situation.

Also, be wary of patients with diabetes mellitus or heart failure when considering compression therapy. In the former, the presence of peripheral neuropathy (reduced sensation of lower legs due to damage to nerves) can result in diminished awareness of pressure-induced skin damage. This group of patients may also have microvascular disease (disease of the small arteries), and when further compromised by external compression, extensive skin death will ensue. Patients with severe heart failure may fare poorly with compression therapy as a result of heart overload. An excessive redistribution of blood will inflict an additional strain to the weakened heart, causing pulmonary oedema and even death.

In summary, an increased awareness amongst health professionals and the public is needed regarding chronic venous disease, which is still underappreciated even within the medical profession. When used appropriately, compression therapy is an effective treatment. It is relatively inexpensive and, with training, easily applied. Chronic venous disease among older people, especially in cases of active venous ulcers, imposes a burden on healthcare budget from hospitalisation costs. Recognising this condition in the early stages and the initiation of compression treatment in the community will help reduce the prevalence of venous ulcers. The humble compression therapy will go a long way in helping patients maintain their independence and quality of life.